Yeah bab.la is usually my first go-to, and if I can’t find a word there, I will try Reverso Context and/or Swan’s dictionary at lektorek.org. One cool thing about Swan’s dictionary also is that you can use wildcards to find any/all words with a particular string in them, and also filter by parts of speech. So if you want to know how many words derive from the root “-ciąg-” for example, you can type *ciąg* into the search bar and it will come up with all words containing that string.

Usage note: though “dziewczę” and “dziewczęta” are forms of the same word, the plural form “dziewczęta” is much more acceptable in everyday speech than the singular “dziewczę”.

In other words, when talking about multiple girls, it’s fine to use both “dziewczyny” and “dziewczęta” (the latter sounds more formal/old-fashioned/naive, but it won’t raise any eyebrows).

If you’re talking about a single girl, “dziewczyna” is the default form, and “dziewczę” is an outlier that is nowadays mostly used when you want to be ironic. I think it’s a bit like calling someone a “damsel” or maybe a “lass” in English.